An FePt alloy can be provided with the fct (Ordered Face Centered Tetragonal) structure which has high crystal magnetic anisotropy by heat-treating at an elevated temperature (for example, at 600° C. or higher), and therefore an FePt alloy has been highlighted as a magnetic recording medium. To make FePt particles smaller and more uniform in the thin film of the FePt alloy, it is proposed that a predetermined quantity of carbon (C) be included into the thin film of the FePt alloy (for example, Patent Literature 1).
However, the formation method of the FePtC thin film, described in the Patent Literature 1, is the method of vapor-depositing Fe, Pt, and C simultaneously on an MgO (100) substrate by using the Fe target of a 2-inch diameter, C target of a 2-inch diameter, and the Pt target of 5 mm in height and width. In this method, it is difficult to obtain the film whose composition is controlled strictly. Additionally, three targets are required and each target needs a cathode, a power supply, etc, and so the cost of equipment becomes high while the preparatory work of sputtering takes time and effort.
In contrast, Patent Literature 2 discloses an FePt—C-based sputtering target that alone can be used to form an FePtC-based thin film without using a plurality of targets and also discloses a method for manufacturing the FePt—C-based sputtering target. Patent Literature 3 discloses an FePt—C-based sputtering target that alone can be used to form an FePtC-based thin film containing a large amount of carbon without using a plurality of targets and also discloses a method for manufacturing the sputtering target.
Patent Literature 4 discloses a sputtering target for forming a magnetic recording medium film. This target contains SiO2 instead of carbon (C) and is formed of a sintered body having a composition represented by a general formula: (FexPt(100-x))(100-y)(SiO2)y, wherein 40≤x≤60 (unit: % by mole) and 5≤y≤30 (unit: % by mole). The sputtering target is characterized in that its structure is composed of an SiO2 phase, an FePt alloy phase formed of a solid solution of Fe and Pt, and an interdiffusion phase that contains Si, O, Fe, and Pt and is formed by interdiffusion of these elements Si, O, Fe, and Pt at the boundary between the SiO2 phase and the FePt alloy phase.
As described above, some sputtering targets have been proposed, each of which alone can be used to form a thin film containing an FePt-based alloy that is receiving attention as a novel magnetic recording medium.
However, it is generally required for a sputtering target to cause a reduced amount of particles during sputtering. This is also required for a sputtering target that alone may be used to form a thin film containing an FePt-based alloy.